I am continuing my thesis research using a murine plasma cell tumor model. Preliminary results show significant decreases in CD4+ T cells in both peripheral Iymph nodes (PLNs) and mesenteric Iymph nodes (MLNs) at the site of the intraperitoneal ascitic tumor. The percentage of B cells (B220+) expressing the maturation marker CD23 is unchanged in both PLNs and MLNs of tumor-bearing mice. I have extended my study to include lymphocytes from bone marrow, focusing on the developing B cell compartment. Identification of the various B cell populations will be done by flow cytometry using fluorescent-conjugated antibodies to B220, HSA, IgD, IgM, Pgp-1, and CD23 with rat IgG as negative control. Functional studies for immunoglobulin secretion will be done on cell culture supernatants by standard sandwich ELISA for mouse ID ano ILM.